<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>dom认知</title>

</head>
<body>
	<div id="app">
		<!-- 头部 -->
		<div class="header">头部</div>
		<!-- 内容 -->
		<div class="content">内容</div>
		
		<!-- 底部 -->
		<div class="footer">底部</div>
	</div>
	<script type="text/javascript">
			console.log("document",document);
			var app = document.getElementById("app");
			console.log("element",app.constructor);
			console.log("HTMLDIVElement:",app instanceof HTMLDivElement);
			console.log("HTMLElement:",app instanceof HTMLDivElement);
			console.log("Element",app instanceof Element);
			console.log("Node:",app instanceof Node);
			console.log("Object:",app instanceof Object);
		</script>
</body>
</html>